As a longtime Twin Peaks fan, watching from my home in Sioux City, IOWA - also where I watched the original series - I can tell you that Yankton Federal Prison is in Yankton, SOUTH DAKOTA - about 50 miles from Sioux City, IOWA. The map Bad Coop was looking at in Episode 1 was correct in the geography of Sioux City being in Iowa. Sioux City is a tri-state area - bordering South Dakota as well as Nebraska. (There is a North Sioux City, SD and a South Sioux City, NE). Making matters even more confusing - Sioux Falls, SOUTH DAKOTA is further north of Yankton (Sioux City is south). The two Sioux towns are often confused in media.